Railroads are under increasing pressure to reduce emissions and to increase fuel efficiency. One of several responses to these forces has been the development of hybrid locomotives. Donnelly has disclosed the use of a battery-dominant hybrid locomotive in U.S. Pat. No. 6,308,639 which is incorporated herein by reference. Hybrid locomotives can reduce emissions and fuel consumption in rail operations such as yard switching but they are less effective for medium haul freight or commuter trains.
In U.S. patent application Ser. No. 11/200,881 filed Aug. 19, 2005 entitled “Locomotive Power Train Architecture”, Donnelly et al. have further disclosed a general electrical architecture for locomotives based on plurality of power sources, fuel and drive train combinations. The power sources may be any combination of engines, fuel cells, energy storage and regenerative braking. This application is also incorporated herein by reference.
Donnelly has also disclosed a method and apparatus for controlling power provided to traction motors by furnishing an individual control circuits for each traction motor in U.S. Pat. No. 6,812,656 which is incorporated herein by reference. Donnelly et al. have disclosed a method of monitoring, synchronizing and optimizing the operation of the locomotive drive train in U.S. patent application Ser. No. 10/649,286; have also disclosed a method of allocating energy amongst members of a consist in U.S. patent application Ser. No. 11/070,848; and have disclosed a method for monitoring, controlling and/or optimizing the emission profile for a hybrid locomotive or consist of hybrid locomotives in U.S. patent application Ser. No. 11/095,036, all of which are also incorporated herein by reference.
Multi-engine locomotives are not new and a number of configurations have been built over the years. Examples are the Baldwin locomotives built in the 1940s and, more recently, a dual engine locomotive built by the French Railway Company, VFLI. In U.S. patent application Ser. No. 11/201,267 filed Aug. 9, 2005 entitled “Multiple Engine Locomotive Configuration”, Donnelly et al. have disclosed a means of packaging engine modules on a multi-engine locomotive that optimizes the power density of the locomotive power plants while reducing emissions and fuel consumption.
Fuel cells are becoming more practical as prime power sources and there is an emerging need for locomotives that can utilize fuel cells and/or engines as prime power systems. There remains a need for a versatile control strategy for multiple prime power sources that can by applied to large vehicles including locomotives. A locomotive comprising multiple-prime power sources and with an appropriate engine control strategy can reduce emissions and fuel consumption over the entire spectrum of railroad applications and does not have to rely on energy storage systems and regenerative braking to gain these advantages.